White light that is reflected by a coloured surface takes on the colour of the surface and becomes the predominant colour of light for the whole room. When lighting a coloured wall with coloured light, this effect can be increased, reversed or inverted.
The colour of light in a room is influenced by the decoration of the room. In comparison to diffuse light, direct light increases the effect of the light when illuminating a coloured surface. The effect of a body colour can be intensified by using coloured light of a similar colour. Strong colour contrasts appear brighter for the same illuminance than a weaker colour contrast. Lesser colour contrasts can be perceived better under brighter lighting. Within closed rooms the effect is hardly perceptible due to the phenomenon of colour constancy.